The precise function of relaxing and contractile proteins in brain is not certain. The objective of this project is to define the regulation of contractile protein activity in brain and specifically as it relates to release and uptake of neurotransmitters by synaptosomal enriched fractions. The coupling in brain of contractile proteins with a relaxing protein complex implies an important interaction which has been revealed in part by our report on the isolation of a complex of a relaxing protein system associated with a contractile protein from synaptosomal enriched fractions. This complex system apparently participates in the release of a putative neurotransmitter. In this proposal it is intended to investigate if the myosin molecules present in the synaptic vesicles, and known to bind Mg2 ion -ATP, may provide a vehicle for the uptake and storage of "Mg2 ion -ATP-biogenic amines" and, if the attachment of synaptosomal membrane actin complex to myosin from synaptic vesicles may facilitate the release of stored bound neurotransmitters concomitant to hydrolysis of ATP. The regulatory protein complex responds to Ca2 ion in a fashion similar to the regulatory proteins of muscle. In brain, however this apparently permits a contractile effect on synaptic vesicles with release of neurotransmitters. In this proposal we intend to study the relaxing proteins by determining their biochemical activity, localize these proteins within the synaptosomal structures by preparing ferritin conjugated antisera against each of these proteins and finally determine their involvement in the mechanisms of uptake, storage and release of chemical transmitters in brain.